Coal processing

ABSTRACT

A COAL HYDROGENATION PROCESS CARRIED OUT IN THE ABSENCE OF HYDROGENATION CATALYST AND IN THE PRESENCE OF WATER.

y 2, 1972 J. J. MCCAULEY 3,660,269

COAL PROCESSING Filed Oct. 14, 1970 GAS l2 l3 r e LLIQUID,

COAL,ASH

I I I H20 SOLVENT -17 -3 COAL H2O I8 INVENTOR JOHN J. M0 CAULEY WWW-4M ATTORNEY United States Patent US. Cl. 2088 6 Claims ABSTRACT OF THE DISCLOSURE A coal hydrogenation process carried out in the absence of hydrogenation catalyst and in the presence of water.

BACKGROUND OF THE INVENTION Heretofore it has been taught to use water in a catalytic hydrogenation reactor, i.e., a reactor employing an externally supplied chemical catalyst such as cobalt molybdate, and the like.

It is desirable from an economic point of view in a coal conversion process to maximize the production of hydrocarbonaceous liquid and to minmize the production of coke forming materials such as asphaltenes because a liquid hydrocarbonaceous product will generally bring a higher return per unit of product than coke and the like.

In addition, it is desirable to minmize the amount of asphaltene present in a hydrocarbonaceous product which must undergo subsequent processing such as fractionation, solvent extraction, and the like because the asphaltenes themselves are difficult to process. Asphaltenes therefore render the material in which they are contained more difiicult to process into the desired liquid hydrocarbonaceous products. This is so because asphaltenes tend to cokify during normal processing.

Therefore, in many applications it is desirable to minimize the asphaltene content of the products of a hydrogenation reactor, thereby simplifying the subsequent processing steps required for this product.

SUMMARY OF THE INVENTION It has now been found that the quantity of asphaltenes present in a coal hydrogenation product are substantially reduced when the hydrogenation reaction is carried out in the absence of hydrogenation catalyst and in the presence of water.

It was surprisingly found that the combination of eliminating hydrogenation catalyst and adding water produced a substantially lower asphaltene content than the combination of hydrogenation catalyst and water.

This invention is useful in converting normally solid coal or similar carbonaceous materials to liquid hydrocarbonaceous products which are useful in producing gasoline, fuel oil, and the like.

Accordingly, it is an object of this invention to provide a new and improved method for carrying out a coal hydrogenation process. It is another object to provide a new and improved process for reducing the amount of asphaltenes contained in products from a coal hydrogenation step. It is another object to provide a new and improved method for liquefying coal without a hydrogenation catalyst. It is another object to provide a new and improved method for producing liquid hydrocarbonaceous products from normally solid coal which products contain reduced amounts of asphaltenes as compared to similar materials produced by the catalytic hydrogenation of coal.

Other aspects, objects, and advantages of this invention will be apparent to those skilled in the art from this disclosure and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION The drawing shows a diagrammatic representation of apparatus useful in practicing this invention.

More specifically, the drawing shows a conventional ebullated bed reactor 1 such as that which is fully and completely disclosed in US. Pat. .Re. 25,770, the disclosure of which is incorporated herein by reference.

A particularly distinguishing feature of the operation of reactor 1 in accordance with this invention is that there is no hydrogenation catalyst such as cobalt molybdate and the like in reactor 1 so that there is no externally supplied hydrogenation catalyst in reactor 1 or employed in the method of this invention.

What is supplied to reactor 1 is comminuted coal by way of pipe 2 and hydrocarbonaceous slurry medium (solvent) by Way of pipe 3 to form a conventional coal slurry which is passed by way of pipe 4 after being heated by heater 5 into a lower portion of reactor 1 for passage upwardly through reactor 1 to eflluent pipe 6. Hydrogen and/or a hydrogen donating liquid and/or gas is supplied by way of pipe 7.

The overhead eflluent from reactor 1 is passed by Way of pipe 6 to a conventional separation system 10 which can include fractionators, cyclones, strippers, and the like and which separates a gaseous hydrocarbonaceous product by Way of pipe 11 and a. substantially liquid hydrocarbonaceous product by way of pipe 12. The hydrocarbonaceous liquid product also contains certain solid residual matter such as unconverted coal, char, coke, and ash. This product can be taken by way of pipe 13 for further treatment whereby the unconverted coal, etc. are separated from the liquid and the liquid fractionated into various grades of products such as residual fuel oil, kerosene, and the like.

Part or all of the product in pipe 12 can be returned by way of pipe 14 to pipe 4 whereby it re-enters reactor 1 for retreatment.

In the operation of reactor 1 in accordance with this invention, reactor 1 can be initially started up completely empty of any material or can contain therein a bed of contact particles which are substantially noncatalytic as to the hydrogenation reaction. These contact particles can be subdivided refractory and/or inert materials such as silica, alumina, quartz, pumice, glass beads, silicon carbide, mullite, zirconia, and the like. The bed can also contain ash, char, coke, unconverted coal, and the like.

Pipe 15 is employed above perforated base 16 so that solids can be removed from the bed to keep it at the desired operating height in reactor 1. Also, if desired, solids can be added to reactor 1 by way of pipe 15.

When reactor 1 is operated with a bed of inert particles, an ebullated bed can be operated within reactor 1 so that the amounts of coal slurry, hydrogen, and the like added to the bed and the velocities of these materials will be adjusted so as to provide and maintain an ebullated bed reactor. One distinction in this operation is, however, that the ebullated bed is composed of a plurality of contact particles that are substantially non-catalytic as regards the hydrogenation reaction taking place in reactor 1.

Of course, more than one reactor 1 can be employed in parallel and/ or series and still be within this invention, the opertaion of one reactor being fully and completely disclosed here only for sake of brevity.

Further in accordance with this invention, there is added to reactor 1 a finite and eifective amount of water up to about 50 weight percent water based on the total weight of the coal being added to reactor 1. It is presently preferred that from about 0.1 to about 50 weight percent of water he added.

The water can be added in any form-liquid, gaseous, and combinations thereof. If added as a liquid the water can be cold, at ambient temperature, or heated. Steam can be added as at least part of the water. The water can be added at any desired position or combination of positions such as those shown by pipes 16, 17, and 18. Water could also be added to the solvent in pipe 3 and/or the hydrogen in pipe 7, and the like so long as the required amount of water is in some manner introduced into reactor 1, preferably in a lower portion thereof. The water can also be supplied at least in part as water that accompanies the raw coal feed. The water can also be incorporated at least in part during comminution of the coal feed.

When externally supplied particles, i.e., particles other than unreacted coal, char, ash, coke, and the like, which return to the reactor by way of pipes 4 and 14, are employed the particles should be subdivided to be in the size range of from about plus 200 mesh (Tyler) to about inch. The ash, coke, etc. which return by way of pipes 4 and 14 can be used in the reactor in the size range in which they are normally produced by the reaction and need not be additionally comminuted or sized before return to reactor 1.

Substantially any coal can be employed in this invention. For example, semi-anthracite, bituminous, semibituminous, sub-bituminous, lignite, peat, and the like can be used.

The slurrying medium (solvent) can be a liquid hydrocarbonaceous material produced by reactor 1 and/or a hydrogen-donor liquid such as Tetralin or partially hydrogenated three or four ring aromatics such as anthracene, naphthalene, phenanthrene, and the like. Other hydrogendonor mediums may be attained by hydrogenation of the hydrocarbonaceous liquid products of reactor 1. Such a medium would boil within the range of from about 400 to about 950 F. The hydrogen-donor liquids are optional from a hydrogenation standpoint because adequate hydrogenation can be obtained with molecular hydrogen alone.

The coal should be comminuted and can have a maximum particle size of minus 8 mesh (Tyler) sieve. The comminuted coal is then mixed with the solvent to form the coal slurry charged to reactor 1. The coal slurry pref erably has a solvent/ coal weight ratio as added to reactor 1 of from about 0.1/1 to about 4/1. The solvent part of the coal slurry can be formed completely or partially from externally added solvent from pipe 3 or hydrocarbonaceous liquid product from pipe 14 or combinations of the two as desired.

Molecular hydrogen and/or a hydrogen donating gas can be charged by way of pipe 7 in amounts such that the hydrogen partial pressure in reactor 1 is maintained at from about 400 to about 3000 p.s.ia.

If a contact particle bed composed of externally added inert particles is employed in reactor 1 there is preferably employed from about to about 70 percent solids by weight in the ebullated bed of reactor 1.

Reactor 1 should be operated at a temperature of from about 500 to about 1000 F. and a total pressure of from about 400 to about 5000 p.s.i.g. The total liquid and gas passing into reactor 1 should be in an amount and at a velocity sufficient to cause the solid particles present in reactor 1, if any, to become an ebullated bed, i.e., so that the solids are in an expanded state and occupy at least 10 percent greater volume than the settled state of the particles mass and are in random motion in the gas-liquid system. It should be noted that in an ebullated bed there is a sharp and finite level of the solid, below which the solid exists at a concentration in excess of 5 pounds per cubic foot of reactor and above which the solid exists at a concentration of less than 0.1 pound per cubic foot of reactor.

EXAMPLE Illinois No. 6 coal comminuted to a minus and plus 300 mesh (Tyler) particle size is mixed with a solvent composed of 675 to 775 F. boiling range oil distilled from the liquid in pipe 12 in a solvent/coal addition weight ratio of 1/1 and subjected to hydrogenation with molecular hydrogen, a temperature of 800 F., and a total pressure of 2200 p.s.i.g. The reaction time was 0.75 hour.

In three of the runs a cobalt molybdate catalyst in the minus 100 and plus 200 mesh (Tyler) size range was used in a coal space velocity of 10.65 pounds of coal per hour per pound of catalyst. In these three runs 1 weight percent, 10 weight percent and 12.5 weight percent water based on the weight of the coal added to the reactor was employed.

In two of the runs there was no externally supplied hydrogenation catalyst. In these two runs, one run used 1 weight percent and the other run used 6 weight percent added water and both runs used the same reaction conditions as the three catalytic runs. The results of these five runs were as follows:

TABLE Asphaltene 1 content Hydrogen Water weight perconsumption, added, cent based weight perweight on MAF cent based on percent coal MAF coal 1 Asphaltenes are defined as that part of the reactor product that is insoluble in pentane.

It can be seen from the above data that with the absence of externally added hydrogenation catalysts and the presence of water, runs 4 and 5, the asphaltene content of the product of the reaction was substantially lower. In the case of runs 1 and 4 which employed the same amount of water, the asphaltene content was substantially lower. In the case of run 5 with only 6 percent water the asphaltene content was substantially lower than runs 2 and 3 both of which had much higher water content. Further, the lower asphaltene content was obtained in runs 4 and 5 with substantially lower hydrogen consumption. Thus, the reaction products of runs 4 and 5 would have been more easily processable based on their lower asphaltene content in that they would have encountered less interference caused by the presence of asphaltene or cokified asphaltenes and the like.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In the hydrogenation of coal wherein a mixture of subdivided coal with hydrocarbonaceous solvent is subjected to hydrogenation conditions of a temperature of from about 500 to about 1000 F. and a pressure of from about 400 to about 5000 p.s.i.g. in an ebullated bed hydrogenation zone, the improvement comprising subjecting said mixture of coal and solvent to said hydrogenation conditions in the presence of an ebullated bed composed of a plurality of particles that are non-catalytic as to said hydrogenation reaction and in the absence of externally supplied hydrogenation catalyst, and adding to said hydrogenation zone a finite, effective amount of water up to about 50 weight percent based on the weight of the coal added to said hydrogenation zone, whereby the production of asphaltenes is decreased.

2. A process according to claim 1 wherein said particles are composed of at least one of silica, alumina, quartz, pumice, glass beads, silicon carbide, mullite, and zirconia.

3. A process according to claim 1 wherein said particles are in the size range of from about plus 200 mesh to about inch.

4. A process according to claim 1 wherein said hydrogeneration conditions include a solvent/ coal addition weight ratio of from about 0.1/1 to about 4/ 1, and a hydrogen addition rate sufi'icient to maintain a hydrogen partial pressure of from about 400 to about 3000 p.s.i.a.

5. A process according to claim 1 wherein said noncatalytic particles are present in the hydrogenation zone in the range of from about 5 to about 70 percent by weight.

6. A process according to claim 1 wherein said solvent boils within the range of from about 400 to about 950 F., and is at least one of a hydrogen-donor hydrocarbonaceous liquid and a hydrocarbonaceous oil derived from a coal and/ or oil hydrogenation process.

References Cited UNITED STATES PATENTS DELB ERT E. GANTZ, Primary Examiner V. OK'EEFE, Assistant Examiner 

